1. Field of the Inventions
The present application relates generally to systems, devices and methods for moving air that are particularly suitable for creating air temperature de-stratification within a room, building, or other structure.
2. Description of the Related Art
The rise of warm air and the sinking of cold air can create significant variation in air temperatures between the ceiling and floor of buildings with conventional heating, ventilation and air conditioning systems. Air temperature stratification is particularly problematic in any spaces with any ceilings such as warehouses, gymnasiums, offices, auditoriums, hangers, commercial buildings, offices, residences with cathedral ceilings, agricultural buildings, and other structures, and can significantly increase heating and air conditioning costs. Structures with both low and high ceiling rooms can often have stagnant or dead air, as well, which can further lead to air temperature stratification problems.
One proposed solution to air temperature stratification is a ceiling fan. Ceiling fans are relatively large rotary fans, with a plurality of blades, mounted near the ceiling. The blades of a ceiling fan have a flat or airfoil shape. The blades have a lift component that pushes air upwards or downwards, depending on the direction of rotation, and a drag component that pushes the air tangentially. The drag component causes tangential or centrifugal flow so that the air being pushed diverges or spreads out. Conventional ceiling fans are generally ineffective as an air de-stratification device in relatively high ceiling rooms because the air pushed by conventional ceiling fans is not maintained in a columnar pattern from the ceiling to the floor, and often disperses or diffuses well above the floor.
Another proposed solution to air temperature stratification is a fan connected to a vertical tube that extends substantially from the ceiling to the floor. The fan can be mounted near the ceiling, near the floor or in between. This type of device can push cooler air up from the floor to the ceiling or warmer air down from the ceiling to the floor. Such devices, when located away from the walls in an open space in a building, interfere with floor space use and are not aesthetically pleasing. When confined to locations only along the walls of an open space, such devices may not effectively circulate air near the center of the open space. Examples of fans connected to vertical tubes are disclosed in U.S. Pat. No. 3,827,342 to Hughes, and U.S. Pat. No. 3,973,479 to Whiteley.
A more practical solution is a device, for example, with a rotary fan that minimizes a rotary component of an air flow while maximizing axial air flow quantity and velocity, thereby providing a column of air that flows from a high ceiling to a floor in a columnar pattern with minimal lateral dispersion without a physical transporting tube. Examples of this type of device are described in U.S. patent application Ser. No. 12/130,909, filed May 30, 2008, and U.S. patent application Ser. No. 12/724,799, filed Mar. 16, 2010, each of which is incorporated in its entirety by reference herein.